The present invention relates to a method of detecting and rejecting poorly filled cigarettes.
The present invention may be used to advantage on a cigarette packing machine input unit--to which the following description refers purely by way of example--of the type wherein an input feedbox comprises an outlet, in turn comprising a reject device, and a number of side by side channels for feeding successive horizontal, superimposed, parallel layers of cigarettes to an extracting device, by which the layers are supplied to a device for forming groups of cigarettes; and wherein the reject device removes any faulty, i.e. at least poorly filled, cigarettes from each channel before the cigarettes are supplied to the group forming device.
On some known packing machines, the cigarettes are not checked until after the groups are formed, and any groups comprising even only one faulty cigarette are rejected.
To reduce the number of rejected cigarettes, and so provide for considerable saving, it has been proposed--in U.S. Pat. No. 4,592,470, for example--to check the cigarettes while still inside the feedbox, and reject any faulty cigarettes before the groups are formed.
The above method presents several drawbacks, mainly on account of the cigarettes being checked during the brief pause in the operation of the extracting device, and not always assuming the same position in front of the detecting device. That is, as the cigarettes must be checked and possibly rejected before reaching the extracting device, the detecting device must be located some distance from the extracting device, so that the two devices are necessarily separated by a column of cigarettes, the height of which varies as a function of humidity, any minor variations in the diameter of the cigarettes, and the traveling speed of the cigarettes (the faster the cigarettes in each column are traveling, the more they are compressed when arrested). As such, the cigarettes may not always be arrested in the same position in front of the detecting device, thus frequently resulting in scanning errors and the rejection of full or, even worse, the acceptance of poorly filled cigarettes.